Not of sound mind; not having the regular use of reason; hence, also, as a noun, an idiot; a lunatic; one devoid of reason, either by nature or from accident.
NON COMPOS MENTIS
Meaning of NON COMPOS MENTIS in English
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012